全文获取类型
收费全文 | 683篇 |
免费 | 21篇 |
国内免费 | 5篇 |
专业分类
化学 | 369篇 |
晶体学 | 7篇 |
力学 | 41篇 |
数学 | 137篇 |
物理学 | 155篇 |
出版年
2023年 | 4篇 |
2022年 | 15篇 |
2021年 | 16篇 |
2020年 | 25篇 |
2019年 | 20篇 |
2018年 | 27篇 |
2017年 | 18篇 |
2016年 | 30篇 |
2015年 | 17篇 |
2014年 | 20篇 |
2013年 | 62篇 |
2012年 | 44篇 |
2011年 | 46篇 |
2010年 | 31篇 |
2009年 | 31篇 |
2008年 | 30篇 |
2007年 | 23篇 |
2006年 | 24篇 |
2005年 | 18篇 |
2004年 | 22篇 |
2003年 | 17篇 |
2002年 | 8篇 |
2001年 | 10篇 |
2000年 | 6篇 |
1999年 | 10篇 |
1998年 | 5篇 |
1997年 | 7篇 |
1996年 | 2篇 |
1995年 | 5篇 |
1994年 | 12篇 |
1993年 | 9篇 |
1992年 | 8篇 |
1991年 | 8篇 |
1990年 | 8篇 |
1989年 | 9篇 |
1988年 | 9篇 |
1987年 | 9篇 |
1986年 | 2篇 |
1985年 | 5篇 |
1984年 | 2篇 |
1983年 | 6篇 |
1982年 | 5篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1976年 | 2篇 |
1975年 | 3篇 |
1974年 | 3篇 |
1967年 | 2篇 |
1956年 | 2篇 |
1955年 | 2篇 |
排序方式: 共有709条查询结果,搜索用时 31 毫秒
51.
Tarek S. Mansour 《合成通讯》2013,43(3-4):659-665
Nitrogen protected amino acid imidazolides undergo facile carbon acylation with magnesium p-nitrobenzylmalonate dihydrate in THF to give pseudodipeptides in 30-79% isolated yield. 相似文献
52.
53.
Toufik Mansour 《Letters in Mathematical Physics》2009,87(1-2):1-18
A q-analogue of the polylogarithm function is introduced via a consideration of the spectral zeta-function of the quantum group SU q (2). We derive certain identities for linear and non-linear combinations of the q-analogue of polylogarithm functions with negative exponents. 相似文献
54.
A nonsimilar boundary layer analysis has been presented for the free convection along a vertical plate embedded in a fluid-saturated
porous medium in the presence of surface mass transfer and internal heat generation. The transformed conservation laws are
solved numerically for the cases of variable wall temperature and variable wall heat flux boundary conditions. Results are
presented for the details of the velocity and temperature fields as well as Nusselt number.
Received on 13 December 1996 相似文献
55.
The nuclear behaviour at high angular momenta is studied by γ-rays emitted in (HI, Xn) reaction. The study of very-high spin states in 153Ho via discrete-line γ-ray spectroscopy and a comparison between the partial decay schemes of 153Ho and the neighbouring 152Dy and 154Er nuclei are discussed in the context of the high spin structure. Second, we present comments on some phenomena observed at high spin states in 153Ho and 152Dy nuclei. 相似文献
56.
A boundary layer analysis has been presented for the interaction of mixed convection with thermal radiation in laminar boundary flow from a vertical wedge in a porous medium saturated with a power-law type non-Newtonian incorporating the variation of permeability and thermal conductivity. The transformed conservation laws are solved numerically for the case of variable surface temperature conditions. The combined convection non-similar parameter we note that =0 and 1 correspond to pure free and forced convection cases. The Rosseland approximation is used to describe the radiative heat flux in energy equation. Velocity and temperature profiles as well as the local Nusselt number are presented. 相似文献
57.
Pressure drop measurements in the laminar and turbulent regions for water flowing through an alternating curved circular tube (x=h sin 2πz/λ) are presented. Using the minimum radius of curvature of this curved tube in place of that of the toroidally curved one in calculating the Dean number (ND=Re(D/2R c )2, it is found that the resulting Dean number can help in characterizing this flow. Also, the ratio between the height and length of the tube waves which represents the degree of waveness affects significantly the pressure drop and the transition Dean number. The following correlations have been found:
- For laminar flow: $$F_w \left( {\frac{{2R_c }}{D}} \right)^{{1 \mathord{\left/ {\vphantom {1 2}} \right. \kern-\nulldelimiterspace} 2}} = F_s \left( {\frac{{2R_c }}{D}} \right)^{{1 \mathord{\left/ {\vphantom {1 2}} \right. \kern-\nulldelimiterspace} 2}} + 0.03,\operatorname{Re}< 2000.$$
- For turbulent flow: $$F_w \left( {\frac{{2R_c }}{D}} \right)^{{1 \mathord{\left/ {\vphantom {1 2}} \right. \kern-\nulldelimiterspace} 2}} = F_s \left( {\frac{{2R_c }}{D}} \right)^{{1 \mathord{\left/ {\vphantom {1 2}} \right. \kern-\nulldelimiterspace} 2}} + 0.005,2000< \operatorname{Re}< 15000.$$
- The transition Dean number: $$ND_{crit} = 5.012 \times 10^3 \left( {\frac{D}{{2R}}} \right)^{2.1} ,0.0111< {D \mathord{\left/ {\vphantom {D {2R_c }}} \right. \kern-\nulldelimiterspace} {2R_c }}< 0.71.$$
58.
F.?S.?IbrahimEmail author M.?A.?Mansour S.?M.?Abdel-Gaied 《Transport in Porous Media》2005,61(1):45-57
The problem of natural convective heat transfer for a non-Newtonian fluid from an impermeable vertical plate embedded in a fluid-saturated porous medium has been analyzed. Non-Darcian, radiative and thermal dispersion effects have been considered in the present analysis. The governing boundary layer equations and boundary conditions are cast into a dimensionless form and simplified by using a similarity transformation. The resulting system of equations is solved by using a double shooting Runge–Kutta method. The effect of viscosity index n, the conduction–radiation parameter R, the non-Darcy parameter Gr*, the thermal dispersion parameter Ds and the suction/injection parameter fw on the fluid velocities, temperatures and the local Nusselt number are discussed. 相似文献
59.
Farzaneh Ahmadi Jahan Bakhsh Raoof Reza Ojani Mehdi Baghayeri Moslem Mansour Lakouraj Hamed Tashakkorian 《催化学报》2015,(3)
Ag nanoparticles were synthesized on the surface of a glassy carbon electrode modified with p‐tert‐butylcalix[4]arene and p‐tert‐butylcalix[6]arene by the deposition of Ag+at an open circuit potential ... 相似文献
60.
A combined experimental and theoretical study has been carried out to investigate mixed-convection heat transfer in a narrow, vertical cavity. The shear force is produced at the left side of a cavity by a belt moving upward that constitutes the sixth wall of the cavity. The left wall of the cavity was cooled and the opposite (right wall) was heated. Hence, the buoyancy force tries to bring the fluid down, and the shear force tends to induce upward fluid flow. The test cell was equipped with two heat exchangers and three thermocouple racks for measuring the temperature distributions at 12 different positions. The temperature field was scanned in the cavity for various flow and temperature boundary conditions. Three-and-two-dimensional laminar models were used to analyze the problem theoretically. The experimental measurements were found to be in good agreement with the numerical predictions. 相似文献